feat(FN-3096): update restart integration store mock for plugin templates

Updates the restart integration test mock to account for plugin template behavior, keeping the test in sync with recent plugin template changes.

Fusion-Task-Id: FN-3096

packages/engine/src/__tests__/restart.integration.test.ts

@@ -212,6 +212,7 @@ function createMockStore(overrides: Record<string, any> = {}) {
     parseStepsFromPrompt: vi.fn().mockResolvedValue([]),
     parseFileScopeFromPrompt: vi.fn().mockResolvedValue([]),
     getSettings: vi.fn().mockResolvedValue({ ...DEFAULT_SETTINGS }),
+    setPluginWorkflowStepTemplates: vi.fn(),
     getRootDir: vi.fn().mockReturnValue("/tmp/root"),
     getFusionDir: vi.fn().mockReturnValue("/tmp/root/.fusion"),
     getTasksDir: vi.fn().mockReturnValue("/tmp/root/.fusion/tasks"),